1. Field of the Invention
The present invention relates to equipment and a method for relaying a TCP (Transmission Control Protocol) session.
2. Description of the Related Art
In recent years, as the Internet is rapidly spreading, a variety of businesses and services using the Internet are being provided. Meanwhile, problems such as the lack of guarantee of communication quality, threats to security, and the growth of communication traffic, have arisen.
Currently, carriers, telecommunications firms and ISPs (Internet Service Providers) which provide service using the Internet each provide a network service using network equipment such as a switch and router which are based on TCP/IP (Internet Protocol). Using this infrastructure, they endeavor to increase the number of access points and broaden the line bandwidth, thereby spreading and improving the Internet.
However, while the Internet is spreading in this way, the needs of current users who demand advanced communication services cannot be satisfied. Since the current Internet is originally an Internet service of “Best Effort” (a communication service without controlling QoS (Quality of Service)), it is not suitable to be applied to businesses and “Rich Contents” on a full scale. Here, “Rich Contents” means contents which have the large amount of real time data, such as movies, radio programs, VoIP (Voice over Internet Protocol).
There has thus been proposed a communication network system capable of providing a variety of communication services to its users without degrading communication performance (refer to JP Laid-Open patent No. 2004-104559). In this communication network system, a provider server is installed on a provider communication network provided by the provider. In addition, service processing equipment is connected to a subscriber/user communication network to which the user terminal is connected. The provider server remotely controls a service processing program stored in the service processing equipment. Based on the rewritable service processing program stored in the service processing equipment, the equipment performs additional control on transfer data transmitted and received between a user terminal and the provider communication network. Herein, the rewritable service processing program is a program for performing transfer/discard of data, conversion of transmitting and receiving addresses, and control of communication quality, etc., on data transmitted and received via the provider communication network.
In the above described conventional communication network system, however, a high-speed communication service is not provided to its users. To perform a smooth and comfortable packet-transmitting/receiving operation by a TCP session on a user terminal, provision of a high-speed communication service is needed, and a process of selectively providing a variety of communication services such as QoS service and security service is further needed. However, a system capable of implementing such process has not been provided until now. In satisfying the needs of the current users demanding advanced communication services, such system is indispensable, and its implementation has been strongly desired. In the RFC 3135, Split Connections are specified, which is the technology for improving TCP performance. In a split connection TCP implementation, the proxy, which is located between end systems and/or proxies (these are called simply end systems), receives a packet from one end system and establishes a corresponding TCP session to another end system. In other words, the proxy terminates the packet from the one end system and originates a separate connection to another end system. This technology can improve the RTT.
However, in this split connection TCP implementation, all packets from the one end system are terminated by the proxy. And the proxy in the RFC 3135 does not have any socket information table or service information table, so the proxy can not selectively terminate the TCP packet from the one end system or provide any types of communication services.